Template matching is a method for detecting an object in an image. In basic template matching, a template for an object to be detected is prepared, and a degree of image feature matching is evaluated between an input image and the template to detect the position and posture of the object in the image. Object detection by template matching is practically used in, for example, inspection and picking in factory automation (FA), robot vision, and monitoring cameras. Faster template matching has recently been needed in response to requests for higher-resolution images and real-time processing of moving images.
To achieve faster template matching without lowering the accuracy of recognition, a reference image of an object to be detected and an input image are scaled down by the same scaling factor, and a degree of image feature matching is evaluated between the scaled-down images (refer to, for example, Patent Literature 1).